City Critters: 5 Animals That Have Adopted The Urban Jungle

1. Frogs In Taiwan Use Storm Drains As Mating Magnifiers

The tiny Mientien tree frogs have taken to using Taiwan's storm drains as echo chambers. "Concrete drains are miniature canyons, but are not analogous to anything in Mientien tree frog natural habitats," Y. Kirk Lin, a biologist at the National Taiwan University, told Live Science. By hopping down into storm drains, these wee croakers can amplify the sound of their calls, which may help attract more mates.

2. Peregrine Falcons Find Homes At The Top Of Buildings

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Peregrine falcons love a good cliff. Their nests -- little more than small divots scraped into ledges -- can be found anywhere from 25 feet to 1,300 feet high. It's no wonder, then, that these birds have taken so readily to bluffs built of steel and concrete. Falcons have been found nesting in skyscrapers from New York City to Seattle. And, like Batman taking to Gotham, some urban falcons have become nocturnal, relying only on artificial light to hunt.

Peregrine falcons love a good cliff. Their nests -- little more than small divots scraped into ledges -- can be found anywhere from 25 feet to 1,300 feet high. It's no wonder, then, that these birds have taken so readily to bluffs built of steel and concrete. Falcons have been found nesting in skyscrapers from New York City to Seattle. And, like Batman taking to Gotham, some urban falcons have become nocturnal, relying only on artificial light to hunt.

3. Metropolitan Ants Have Adapted To Beat The Heat

Ants in Sao Paolo, Brazil, can tolerate heat better than their rural neighbors, according to a 2007 study in the journal PLOS ONE. Although cities are often much warmer than the surrounding areas -- up to 22 F warmer -- urban leaf-cutter ants are built to handle these hotter temperatures. Compared with the rural insects, it took 20 percent longer for very high heat to knock out the urban ants.

4. Sea Lions Sprawl Out All Over San Francisco's Pier 39

Sea lions haul out of the water to huddle on San Francisco's Pier 39. They'll gather together in large groups as a social gathering, but also to keep warm, according to University of California, Santa Cruz biologists.

5. Swallows Trigger Automatic Doors To Swoop In And Out Of Their Nest

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It's not just falcons that have adopted buildings as their own avian Airbnbs. These swallows will flit in front of a motion sensor, triggering the doors to open to their nesting site, safe in a parking garage at the University of Victoria, Canada.